The present invention relates to a device for looping raw dough products, in particular strands of dough pre-shaped to produce pretzels.
Devices for looping pretzels is known from the prior art. They generally comprise apparatus for supplying raw dough products and a loop-forming device for looping the raw dough products in order to produce pretzel-shaped raw dough products. Optionally a device may be provided for stretching and/or aligning the raw dough products generally supplied to the loop-forming device in a U-shape with the branches (legs) of the U in front or forward as viewed in the direction of conveyor movement.
In devices known from the prior art for looping pretzels, sensors are provided which detect the ends of the strands of dough for the purpose of aligning and/or for the purpose of controlling gripping devices of the loop-forming device.
Such sensors are generally designed as single-path or reflex light barriers. For example, in DE 10 2009 0006 479 A1, a device is disclosed for looping raw dough products, in particular for producing pretzels, which comprises a loop-forming device and a conveying device for the raw dough products. At the end of the conveying device facing the loop-forming device in each case a component is provided which serves as a “dough receiver” for the arriving (leading) end of a raw dough product and includes, and/or is operatively connected to, a sensor for detecting the raw dough product.
Another device for producing pretzels is disclosed in DE 198 52 046 C1. This device comprises a supply arrangement, a discharge arrangement for the completed pretzel loops, a working platform and a robot arm or linear robot for looping the raw dough products. The robot arm or linear robot is provided on its underside with grippers or suction pads for looping the strand of dough to form a pretzel. In this case, the known device comprises at least one sensor for ascertaining the end of the strand of dough, and a control device that coordinates the cooperating movements of the movable individual parts of the device using the signals thereof.
Apparatus for stretching and/or aligning raw dough products is disclosed in DE 10 2010 008 024.1. This apparatus comprises a sensor unit having two sensors for detecting the ends of a strand of dough of the arriving raw dough products. In the case where the sensors for detecting the ends of a strand of dough in the conveying direction are arranged upstream of the means for aligning and/or stretching the raw dough products, the known device comprises a light barrier for detecting the raw dough product and. Thus. the moment in time when the transverse part of the U-shaped raw dough products, arriving with the branches of the U in front, passes through the light barrier.
EP 1 935 246 B1 discloses a system for measuring and aligning strands of dough in terms of their length and position for use in pretzel looping machines or other dough preparation machines. The system comprises a scanning device for individually identifying each of two end portions of a strand of dough protruding in the conveying direction, the scanning device for each end portion of a strand of dough in each case including a set, or group, or a row aligned therewith of a plurality of parallel energy sources and energy sensors or receivers. The energy sources and/or sensors or receivers thus grouped together are arranged and configured on both sides of the through-passage of the strand of dough in predetermined numbers and/or for emitting a predetermined quantity of energy. In this case, the control of the system in terms of circuitry and programming is designed and set up so that a quantity of energy, emitted by a group of energy sources towards the respective end portion of a strand of dough, may be compared with the amount of energy detected or received, and the length and/or position of the strand of dough may be derived from the comparison, and the drive unit of the system may be activated to maintain a predetermined position of the strand of dough.
The use of sensors known from the prior art which, as already explained, are designed as single-path or reflex light barriers or energy sources with associated energy receivers, results in increased costs and in complex assembly.